Alternately and alternatively

Alternate means ‘every second’ in turns.

We spend alternate weekends at our farm house.

Alternatively can mean ‘different’, ‘instead’ or ‘on the other hand’.

You can go by air, or alternatively you can hire a taxi.

As and since

Both as and since can be used to refer to the reason for something. Note that these are used when the reason is already known to the reader or the listener.

As she was not there, I left a message with her mother.

As it is raining again, we will have to cancel the match.

Since she had not studied well, she could not score good marks.

Note that as- and since- clauses usually come at the beginning of sentences.

As- and since- clauses are formal. In an informal style we use a so-clause.

She was not there, so I left a message with her mother.

It is raining again, so we will have to cancel the match.

Because clauses are used when the reason is the most important part of the sentence.

Because I was ill for six months, I lost my job.

Back and again

Back and again have similar meanings.

Back is an adverb particle. When used with a verb, it suggests a return to an earlier situation. Again cannot be used with a verb in this way.

Give me my money back. (NOT Give me my money again.)

This cake isn’t good. I am taking it back to the shop. (NOT I am taking it again to the shop.)

Again

When used with a verb, again suggests repetition.

His behavior was very disgusting. I am not going to invite him again. (NOT I am not going to invite him back.)

I am wondering why she never invites us back to her parties.

Bring and take

Bring is used for movements to the place where the speaker or the hearer is. Take is used for movements to other places.

Bring me a cup of coffee. (Here we are talking about moving a cup of coffee to the place where the speaker is.)

Bring me that file. (NOT Take me that file.)

Can you take the car to the garage?